preliminary study of electron/ hadron discrimination with the neucal detector

Preliminary study of electron/hadron discrimination with the NEUCAL detector

Lorenzo BonechiUniversity and INFN – Florence (Italy)

11th ICATPP - Conference on Astroparticle, Particle, Space Physics, Detectors and Medical Physics Applications

5-9 October 2009, Villa Olmo (Co), Italy

The NEUCAL working group

O. Adriani1,2, L. Bonechi1,2, M. Bongi2, S. Bottai2,G. Castellini3, R. D’Alessandro1,2, M. Grandi2, P. Papini2,

S. Ricciarini2, G. Sguazzoni2, G. Sorichetti1, P. Sona1,2,P. Spillantini1,2, E. Vannuccini2, A. Viciani2

1) University of Florence2) INFN Section of Florence3) IFAC – CNR, Florence

2ICATPP 2009 - Lorenzo Bonechi5 October 2009

Outline of this presentation

• Basic ideas– e/hadrons discrimination with e.m. calorimeters– Use of neutron detectors (PAMELA experiment)– The new NEUCAL concept

• Simulations• The prototype detector

– Description of apparatus and assembling

• Test beam at CERN SPS (August 2009)– Event show and first preliminary comparison with the GEANT4

simulation

3ICATPP 2009 - Lorenzo Bonechi5 October 2009

PART 1

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Basic ideas

e/hadrons discrimination in HEP• Common requirement for HEP experiments

– particularly important for those devoted to Astroparticle Physics• Electromagnetic calorimeters

– very good discrimination capability in a wide energy range

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18 GeV/celectron

36 GeV/cproton

Two events detected by the PAMELA space experiment

SILICON TRACKERMAGNET

TRIG. SCINTI.

E.M. CALO

The situation at higher energy

• Interacting protons with energy beyond few hundreds GeV can be tagged as electrons due to– similar energy release in calorimeter than electrons– similar shower development than electrons

• It is not possible, especially for space experiments, to increase too much the calorimeter depth – strong limitation in weight and power consumption

• Complementary detectors, like trackers, cannot help easily at these energies

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The use of a neutron counter in PAMELA• Neutron production:

– Protons: nuclear excitation, hadronic interaction and Giant Resonance– Electrons: only through the Giant Resonance

• Different yield in neutron production are expected for e.m. or hadronic showers

• New idea in PAMELA: use a neutron counter as the final stage of the apparatus (beyond calorimeter)

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18 GeV/celectron

36 GeV/cproton

New idea in NEUCAL:• Study of the moderation phase using an active moderator• Standard plastic scintillators are rich in hydrogen and then suitable as

moderators (Eljen EJ-230 [CH2CH(C6H4CH3)]n )• Detection of:

– signals due to neutron elastic/inelastic scattering– signals due to absorption of neutrons by

3He (proportional tubes)

Detection of neutrons produced inside the calorimeter: the NEUCAL concept

PAMELA:• Moderation of neutrons by means of passive moderator (polyethylene layers)• 3He proportional tubes to absorb thermal neutrons and detect signals due to

the ionization of products inside gasn + 3He 3H + p (Q = 0.764 MeV)

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SCINTPMT orSi-PMT

3He tube

n

PART 2

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Simulation

Few details and results• First results based on FLUKA, now implementing also

GEANT4 simulation• Detector geometry has been dimensioned for application

together with a 30 X0 calorimeter (CALET experiment)– NEUCAL is placed downstream a 30 X0 deep homogeneous BGO

calorimeter

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12 scintillator

layers

3He Tubes (1 cm diam.)

30 X0

NEUCAL

BGOtiles

Distribution of number of neutrons

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400 GeV electrons1 TeV protons

Note: energy release inside the BGO calorimeter is almost the same for 1TeV protons and 400 GeV electrons.

FLUKA FLUKA

Scatter plot: arrival time vs neutron energy

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Almost all neutrons exit from the calorimeter within a few microseconds, but thermalization inside neucal can take hundreds microseconds

Outgoing neutron energy Log (E(GeV)/1GeV)

Arr

ival

tim

e (s

econ

ds)

1 G

eV

1 M

eV

100 ns

1 s

1 ke

V

10 ns

Expected performance (comparison FLUKA/GEANT4)

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FLUKA simulated energy release inside one scintillator layerSee also: S.Bottai et al., at Frontier Detector for Frontier Physics, La Biodola (Elba), 24-30 May 2009

Neutrons up to few MeV kinetic energy are moderated and detected with high efficiency.

At 10 MeV 70% of neutrons gives detectable signals.Only 10% are fully moderated to be detectable by the 3He Tubes

1 MeV neutrons

10 MeV neutrons

ENTR

IES

ENTR

IES

PART 3

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The prototype detector

Production of scintillators

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One side covered with aluminized tape

Scintillator material:Eljen Technology, type EJ-230 (PVT, equivalent to BC-408)

Light guides: simple plexiglas

Production of prototype detecting modules

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Optical grease: Saint Gobain BC-630

PMT Hamamatsu

R5946

Production of the first module

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3He proportional counter tube: Canberra 12NH25/1

1 cm diameter

Prototype assembly

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3x3 matrix of scintillator modules with 5 3He proportional counter tubes integrated

1 cm diameter3He tubes

scintillatorlight guide

PMT

Digitalization electronics

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CAEN V1731 board VME standard 8 ch, 500MS/s 8 bit ADC 2MB/ch memory (few ms digitization) 16 ns jitter On-board data compression (Zero Suppression Encoding)

CAEN V1720 board VME standard 8 ch, 250MS/s 12 bit ADC 2MB/ch memory (few ms digitization) 32 ns jitter On-board data compression (Zero Suppression Encoding)

PART 4

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Test beam at CERN SPS (August 2009)

Integration of the NEUCAL prototype with a 16 X0 tungsten calorimeter (25 July 2009)

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NEUCAL

CALORIMETER

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CALORIMETER

Beam test details

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• CERN SPS, line H4 (one week test)• Beam type – energy - # of events:

– Pions 350 GeV ( 230000 events)– electrons 100 GeV ( 240000 events)– electrons 150 GeV ( 50000 events)– muons 150 GeV (130000 events)

• Data collected in different configurations– scan of detector (beam impact point)– different working parameters

• PMTs and tubes voltages• Digitizer boards parameters (thresholds, data compression…)

• Next slides report a comparison of data with GEANT4 simul. for electron and pion events taken in the following configurations:

Detectors’ configuration

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ELECTRON

beam

PION

beam

Total thickness upstream NEUCAL: 16 X0

Total thickness upstream NEUCAL: (16+13) X0

NEUCAL

16 X0

WCALO

NEUCAL

16 X0

WCALO

9 X0

Pb2.

25 X 0

PbW

O 4`

30

• Digitalization of scint. output for a long time interval (1ms)• Look for signals which are not in time with other signals on

other channels:– Avoid the prompt signals due to charged particles coming directly from the shower– Avoid single charged particles giving signals on more then one scintillator (non interacting

hadrons entering the detector

How to find neutron signals?

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Trigger

PromptsignalScint.

A

Particlesignal

t=0 t=1ms

Promptsignal

t10us

Scint.B

Particlesignal

?time

time

Digitalization of one muon event

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Scintillators 3He tubes

1 2

4 5

3

DOWNSTREAM

UPSTREAM Trigger signals

t = 0

t ~700ns

Bounces are due to additional filters on the digitizer inputs to solve a problem of firmware (loss of fast signals)

Digitalization of one electron event

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Scintillators 3He tubes

1 2

4 5

3

DOWNSTREAM

UPSTREAM Trigger signals

All signals rise at t = 0 (prompt shower secondaries)

Digitalization of pion events (1)

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Scintillators 3He tubes

1 2

4 5

3

DOWNSTREAM

UPSTREAM Trigger signals

t ~34 s

t ~100 s

Digitalization of pion events (2)

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Scintillators 3He tubes

1 2

4 5

3

DOWNSTREAM

UPSTREAM Trigger signals

t ~28.5s t ~46.8s

t ~250s

Digitalization of pion events (3)

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Scintillators 3He tubes

1 2

4 5

3

DOWNSTREAM

UPSTREAM Trigger signals

t ~14.6s t ~170s

t ~12.6s

t ~250s

First preliminary comparison data/MC

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33000 events- “single” signals- one single central

PMTGEANT4

data

Instrumental effect

? Spurious particles

ENER

GY

ARRIVAL TIME

100 GeV ELECTRONS

First preliminary comparison data/MC

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75000 events- “single” signals- one single central

PMTGEANT4

dataSpurious particles?

ENER

GY

ARRIVAL TIME

350 GeV PIONS

Comparison data/MC: signal energy distribution

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33000 ELECTRON events

75000 PION events

GEANT4

GEANT4

PRELIMINARY

PRELIMINARY

Comparison data/MC: time distribution

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33000 ELECTRON events

75000 PION events GEANT4

GEANT4

PRELIMINARY

Conclusions• A new neutron detector, NEUCAL, is under study for particle

identification purposes

• Its aim is to help e.m. calorimeters in e/hadron separation at H.E.

• New idea: use an active moderator (plastic scintillator) to moderate the neutrons and detect their signals simoultaneously

• A prototype has been developed e tested with charged particles during a beam test at CERN SPS (August 2009)

• First very preliminary comparison between data and GEANT4 simulation shows substantial agreement, even if some effects is not yet understood (instrumental effect?)

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Backup slides

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Expected performance

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Simulated energy release inside NEUCAL (12 scintillator layers detector)S.Bottai et al., at Frontier Detector for Frontier Physics,

La Biodola (Elba), 24-30 May 2009

Neutrons up to few MeV kinetic energy are moderated and detected with high efficiency. At 10 MeV 70% of neutrons gives detectable signals.Only 10% are fully moderated to be detectable by the 3He Tubes

Filter

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